An imagable article comprising a photosensitive composition comprising a polymer having acid labile pendant groups

ABSTRACT

Photosensitive compositions containing a photoinitiator which generates an acid upon exposure to light and a polymer containing pendant alkoxy alkyl ester groups. Also disclosed are imageable articles containing the photosensitive compositions of the present invention coated on a substrate as well as processes for forming an imaged article.

This is a division of application Ser. No. 07/618,213 filed Nov. 26,1990 now U.S. Pat. No. 5,102,771.

FIELD OF THE INVENTION

This invention relates to photosensitive compositions. It also relatesto imageable articles containing novel photosensitive compositions.

BACKGROUND OF THE INVENTION

Lithographic processes generally employ at least two steps to prepare aplate for use in a printing press, namely exposure of a plate coatedwith a photosensitive composition to a positive or negative light sourceto create a photoimage and a subsequent development step. Typically in anegative-acting system, the development step involves washing awaymaterial from the plate which was unexposed to the light source with theaid of a developer solution which may be highly alkaline, e.g. pH of 13,and based on an organic solvent. Alternatively, heating has sometimesbeen employed to effect development of the photoimage.

Both of the above-described development processes, though, suffer fromthe drawback of being relatively time-consuming and expensive in someinstances. Furthermore, when volatile organic or strongly alkalinedeveloper solutions are used, their disposal presents an environmentalproblem.

What have been needed in the industry, therefore, are photosensitivecompositions which can be used in development processes which do nothave the above-described drawbacks.

A variety of different materials have been used in photosensitivecompositions in the past. Photosensitive compositions employing polymerswith pendant acid sensitive moieties have been described in the art(Ito, H.; Ueda, M. Macromolecules 1988, 21, 1475-82). o-Nitrobenzylsubstituted polyacrylates have been described in U.S. Pat. No. 3,849,137(Nov. 19, 1974; Barzynski). t-Butyl substituted polyacrylates have alsobeen reported (Ito, H.; Willson, C. G. in Proc. SPIE-Int. Soc. Opt. Eng.1987, 771, 24; and U.S. Pat. No. 4,491,628 (Jan. 1, 1985; Ito).

U.S. Pat. No. 4,963,463 (Koshiba et al.) claims a radiation sensitiveresin composition comprising an alkali soluble resin, an o-quinonediazide, an aci sensitive esters of nitrobenzyl or cyanobenzyl alcohol.

End-capped polyphthalaldehyde has been employed in imaging systens incombination with onium salts which were used as a source ofphotogenerated acid (Ito, H.; Willson, C. G. Polym. Eng. Sci. 1983, 23,1013). Photoresists based on thermal polycarbonate degradation in thepresence of photogenerated acid have also been described (Frechet, J. M.J.; Bouchard, F.; Houlihan, F. M.; Kryczka, B.; Eichler, E.; Clecak, N.;Willson, C. G. J. Imag. Sci. 1986, 30, 59). Both of these systemsfunction by cleavage of the polymer backbone.

Canadian Patent No. 672,947 (Canadian Industries Ltd.) describesprotective films comprising copolymers of tetrahydropyran-2-ylacrylates, and glycidyl esters of acrylates. These films are thermallyprocessed, thereby effecting cleavage of the tetrahydropyran-2-ylgroups, and subsequently causing cross-linking of the carboxylic acidand the epoxy residues.

Benzyl, benzhydryl, and triphenylmethyl acrylates have been imaged usinghigh energy radiation (e.g., electron beam, x-ray, and ion beam) sourcesfollowed by development with aqueous alkaline solutions as described inJapanese published applications 59-075244 (Apr. 27, 1984; Hitachi,Ltd.), and 58-068743 (Apr. 23, 1983; Hitachi, Ltd.).

Dimethylbenzyl methacrylates have been employed in combination withiodonium salts as deep-UV photoresists (Ito, H. Polym. Mater. Sci. Eng.1989, 60, 142).

α-Substituted benzyl methacrylate polymers have been photoimaged anddeveloped with an alkaline developer (Ito, H.; Ueda, M.; Ebina, M. ACSSymp. Ser. 1989, 412, 57-73).

Japanese published applications 63-256492 (Oct. 24, 1988; Fuji PhotoFilm Co., Ltd.) and 63-317388 (Dec. 26, 1988; Fuji Photo Film Co., Ltd.)describe several direct-image lithographic plate formulations employingpolymers having side-chain groups which, following an etchingdevelopment step, cleave to form hydroxyl and carboxyl groups.

Japanese published patent applications 53-094691 (Oct. 24, 1989, FujiPhoto Film) and 53-100192 (Oct. 30, 1989, Fuji Photo Film) describelithographic plates containing polymers with acid labile groupsincluding some alkoxyalkyl esters. The plates also contain cross-linkingagents which appear to cross-link with carboxylic acid residues as theyare formed. These plates appear to act in a negative-tone and mayinvolve a development step.

Japanese published application 62-299,313 (Jun. 1, 1989, MatsushitaElectric Industrial) describes the use of polymers containing acidanhydride residues in combination with o-nitrobenzyl esters ofcarboxylic acids. These polymers are sensitive only to UV radiation.

Summary of the Invention

The novel photosensitive compositions of the present invention comprise:(a) a photoinitiator which generates an acid upon exposure to radiation;and (b) a polymer having acid labile groups pendant from the polymerbackbone, said pendant groups being represented by the formula ##STR1##wherein: R¹ and R² each represent H or an alkyl group with 1 to 18carbon atoms with the proviso that at least one of R¹ and R² must behydrogen; R³ represents an alkyl group with 1 to 18 carbon atoms; or anytwo of R¹, R², and R³ may together form a substituted or unsubstitutedring having from 3 to 36 carbon atoms; and T represents a divalentlinking group bonded to the polymer backbone contains a total of from 0(a covalent bond) or 1 to about 18 carbon atoms where up to one of eachthree carbon atoms may be replaced by oxygen, nitrogen, or sulfur atomsor combinations thereof.

In another embodiment of the present invention, an imageable article isprovided which comprises a substrate coated with the above-describedphotosensitive composition.

In still other embodiments of the present invention, processes forforming an imaged article are provided.

One inventive process involves the formation of an imaged articlecomprising exposing an imageable article (as disclosed herein earlier)to radiation within a range absorbed by the photoinitiator present inthe imageable article to form a latent image bearing article andthereafter, applying ink to the latent image bearing article, therebyforming an imaged article. An alternative to the above process involvescontacting the latent image bearing article with a dye, instead of inkto form an imaged article.

Another inventive process for the formation of an imaged articlecomprises the steps of exposing an imageable article (as disclosedherein above) to a range absorbed by the photoinitiator present in theimageable article thereby forming a first latent image bearing article;contacting the first latent image bearing article with a hydrophilizingagent to form a second latent image bearing article; and thereafter,contacting the second latent image bearing article with a dye solutionto form an imaged article. In an alternate embodiment to this process,the second latent image bearing article is contacted with ink, insteadof a dye, to form an imaged article.

Also provided is a process for forming and fixing an imaged articlecomprising the steps of:

a) exposing an imageable article to radiation within a range absorbed bysaid photoinitiator to form a first latent bearing article;

b) heating said first latent image bearing article to a temperaturegreater than about 100° C. to form a second latent image bearingarticle, and

c) cooling said heated latent image bearing article to below 40° C. toform a third latent image bearing article, and

d) exposing said modified latent image bearing article to white light toform a fourth latent image bearing article, and

e) contacting said fourth latent image bearing article withhydrophilizing agent to form a fifth latent image bearing article, and

f) applying ink to said fifth latent image bearing article to form animaged article.

The photosensitive compostions of the present invention do not have thepreviously discussed disadvantages and drawbacks associated with the useof conventional materials. Because the inventive compositions can beused in either self-developing processes or ones which require onlyneutral aqueous developing conditions, their use is more economical,efficient, and environmentally sound than the use of conventionalmaterials.

Other aspects, embodiments, and advantages of the present invention willbe apparent from the detailed description, the examples, and theappended claims.

DETAILED DESCRIPTION OF THE INVENTION

The photosensitive composition of the present invention comprises aphotoinitiator which generates an acid upon exposure to radiation and apolymer having acid labile groups pendant from the polymer backbone, thependant acid labile groups being represented by the general formula:##STR2## wherein

R¹ and R² each represent H or an alkyl group with 1 to 18 carbon atomswith the proviso that at least one of R¹ and R² must be hydrogen; R³represents an alkyl group with 1 to 18 carbons; or any two of R¹, R₂,and R³ may together form a substituted or unsubstituted ring having from3 to 36 carbon atoms. With regard to R¹, R², and R³, preferred alkylgroups are methyl and ethyl. Preferred ring structures are furanyl,puranyl, and oxabicyclooctyl. T represents a divalent linking groupbonded to the polymer backbone and contains from about 0 to about 18carbon atoms where up to one of each three carbon atoms may be replacedwith oxygen, nitrogen, or sulfur atoms or combinations thereof.Preferably, T should contain no functional groups which are more basicthan the alkoxyalkyl ester moiety employed in the present invention.Representative examples of such functional groups (which are more basicthan the alkoxyalkyl ester moiety) include, but are not limited to,amines, alkoxides, sulfides, amides, urethanes, imides, etc.Non-limiting examples of T include methylidene, 1,5-pentanediyl,2-oxo-propanediyl, phenylene, and the like.

The polymers of the present invention are preferably derived from anynon-basic (i.e., not containing 1°, 2°, or 3° amines or phosphines)polymer backbone, and may be prepared by any of the known in the artmethods for preparing polymers (such as free radical, anionic,condensation, and cationic polymerization). Non-limiting examples ofnon-basic polymer backbones are polyacrylates, polymethacrylates,polystyrenes, acrylonitrile-styrene copolymers, butadiene-styrenecopolymers, polyolefins (e.g. polyethylene, polypropylene,polyisobutylene, etc.), polyesters, polyethers, polycarbonates,polysulfides, and the like. Examples of basic polymer backbones arethose containing 1°, 2°, or 3° amines or phosphines; of 1° or 2° amides.Preferred polymer backbones are derived from free radical polymerizedpolymers. Particularly preferred polymer backbones are polyacrylates andpolymethacrylates. Additionally, it may be desirable in someapplications that the polymer matrix be cross-linked, while in otherinstances it may be preferable that there be no cross-linking.

Alkoxyalkyl ester moieties may be either incorporated within monomerunits prior to polymerization or attached to already formed polymerbackbones using methods well known in the chemical art. For example, incases in which an active hydrogen atom is present on the polymerbackbone (for example, --OH, --C(O)CH₂ C(O)--, --SH, and the like),deprotonation with a strong base (such as sodium hydride, lithiumdiisopropylamide, potassium t-butoxide, or any other base havingsufficient strength to abstract the active hydrogen atom), followed bycondensation with alkoxyalkyl ester moieties having reactive groups suchas epoxy, haloacyl, carboxyalkyl, and the like may be used to preparedthe polymers of the present invention. In cases in which olefinicunsaturation is present, alkoxyalkyl ester moieties having alkenylsubstituents may be added by reactions such as Diels-Alder 4+2 thermalcycloadditions or 2+2 photocycloaddition. In still other cases in whichno recognized functionality is present (e.g., polyethylene,polypropylene, etc.), one may corona treat or otherwise oxidize saidpolymer to provide active hydrogen sites on the polymer backbone.

The photoinitiator used herein is one which generates acid upon exposureto radiation. Many such substances are known in the photoimaging artincluding, but not limited to, various onium compounds (e.g., sulfonium,iodonium, diazonium, etc.; particularly aryl derivatives thereof), andvarious organic compounds with photolabile halogen atoms(α-halo-p-nitrotoluenes, α-halomethyl-s-triazines, carbon tetrabromide,etc.) While the choice of photoinitiator is not critical, it isdesirable that the photoinitiator have limited solubility in water inorder to provide maximal inkability.

In a preferred embodiment, the photoinitiator is a substituted orunsubstituted diaryliodonium salt generally described by the formulae:##STR3## wherein A and B are substituted or unsubstituted aryl groupswith a total of from 4 to 20 carbon atoms (e.g., substituted orunsubstituted phenyl, napthyl, thienyl, and furanyl). W is selected fromthe group consisting of a carbon-carbon bond; oxygen; sulfur; ##STR4##wherein R⁶ is aryl (e.g., 6 to 20 carbon atoms) or acyl (e.g., 2 to 20carbon atoms), or R⁷ --C--R⁸ wherein R⁷ and R⁸ are individually selectedfrom hydrogen, alkyl groups of 1 to 4 carbon atoms, and alkenyl groupsof 2 to 4 carbon atoms,

p is 0 or 1; and

Q⁻ is any anion capable of forming a stable salt with diphenyliodoniumcation at room temperature, i.e., the anion must have a pK_(a) less thanabout 16, and an oxidation potential of greater than about 0.7 V.Preferred anions Q⁻ are complex halogenated metal anions such ashexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate; boratessuch as tetrafluoroborate and tetraphenylborate. Particularly preferredanions are hexafluorophosphate, hexafluoroantimonate, hexfluoroarsenate,and tetrafluoroborate.

Non-limiting examples of suitable iodonium salts are salts ofdiphenyliodonium, dinaphthyliodonium, di(4-chlorophenyl)iodonium,tolyl(dodecylphenyl)iodonium, naphthylphenyliodonium salts,4-(trifluoromethylphenyl)phenyliodonium, 4-ethylphenylphenyliodonium,di(4-acetylphenyl)iodonium, tolylphenyliodonium, anisyphenyliodonium,4-butoxyphenylphenyliodonium, di(4-phenylphenyl)iodonium,di(carbomethoxyphenyl)iodonium, and the like. Diphenyliodonium salts arepreferred.

The photolyzable organic halogen compounds which are useful in thepresent invention are those that upon exposure to radiation dissociateat one or more carbon-halogen bonds to form free radicals. Thecarbon-halogen bond dissociation energy should be between about 40 and70 kcal/mole as taught in U.S. Pat. Nos. 3,515,552 (June 2, 1970;Smith). Preferred photolyzable organic halogen compounds have from 1 to40 carbon atoms, are non-gaseous at room temperature, and have apolarographic half-wave reduction potential greater than about -0.9 V asdescribed in U.S. Pat. Nos. 3,640,718 (Feb. 8 1972; Smith) and 3,617,288(Nov. 2, 1971; Hartman).

Examples of photolyzable organic halogen compounds are hexabromoethane,α,α,α',α'-tetrabromoxylene, carbon tetrabromide,m-nitro(tribromoacetyl)benzene, α,α,α-trichloroacetanilide,trichloromethylsulfonylbenzene, tribromoquinaldine,bis(pentachloropentadiene), tribromomethylquinoxaline,α,α-dibromo-p-nitrotoluene, α,α,α,α',α',α'-hexachloro-p-xylene,dibromotetrachloroethane, pentabromoethane, dibromodibenzoylmethane,carbon tetraiodide, halomethyl-s-trizines such as2,4-bis(trichloromethyl)-6-methyl-s-triazine,2,4,6-tris(trichloromethyl)-s-triazine, and2,4-bis(trichloromethyl)-6-(p-methoxystyryl)-s-triazine, etc.

The iodonium salts or photolyzable organic halogen compounds employed inthe present invention may be either exposed to ultraviolet radiation orsensitized into the visible spectrum. Wavelengths between 250 nm and 900nm inclusive may be used. Compounds useful as sensitizing dyes of thisinvention include, but are not limited to aryl nitrones, xanthenes,anthraquinones, substituted diaryl- and triarylmethanes, methines,merocyanines, and polymethines, thiazoles, substituted and unsubstitutedpolycyclic aromatic hydrocarbons, and pyrylium dyes.

In some instances it is desirable to add at least one additional polymerto the photosensitive compositions of the present invention. Thepolymers generate additional hydrophilic functionality upon exposure tolight and treatment with aqueous solutions; therefore, serve to increasethe differential in wettability between the exposed and unexposedregions of the photosensitive composition. The additional polymer may bepresent in amounts up to 90 percent by weight, preferably not more than50 percent. Preferably, the additional polymer is a homo- or co-polymerof an acid anhydride. Most preferably, the additional polymer is a homo-or co-polymer of maleic anhydride (e.g., GANTREZ™ AN139 available fromGAF Corp., Wayne, NJ).

Additionally, it may be desirable to treat the photosensitivecompositions of the present invention with at least one hydrophilizingagent subsequent to exposure. Suitable hydrophilizing agents increasethe wettability in exposed regions without affecting the wettability inunexposed regions of the photosensitive composition, thereby increasingthe differential in wettability between exposed and unexposed regions.Preferably, the at least one hydrophilizing agent is a basic materialcompound. Most preferably, the basic material is an 1°, 2°, 3°, or 4°amine-substituted sulfonic acid or its salt having from 2 to 18 carbonatoms (e.g., 4-morpholinepropanesulfonic acid,β-hydroxy-4-morpholinepropanesulfonic acid salt,4-morpholineethanesulfonic acid, sodium 4-morpholinepropanesulfonate,sodium cysteate, pyridinium, etc.), an 1°, 2°, 3°, or 4°amine-substituted alcohol (e.g.,tetrakis(2-hydroxyethyl)ethylenediamine, 2-amino-1,3-propanediol,triethanolamine, or its acid salts, etc.) or amine-substitutedcarboxylic acid (e.g., glycine, alanine, 3-dimethylaminopropanoic acid,etc.) The method of treatment is not critical and may be accomplishedfor example by wiping or spraying the hydrophilizing agent onto theexposed plate, or by dipping the exposed plate into a solution of thehydrophilizing agent, or by means of a fountain solution when used on apress. Additionally, an acid-base indicator dye can be added to theformulation. This can serve to give the plate a color initially as wellas to give a printout image upon image-wise exposure. A furtheradvantage of having visible dye present is that it tends to increase thehandling time under fluorescent lights before the plate becomes overexposed.

The photosensitive compositions of the present invention are generallycoated onto a substrate prior to use in an imaging application. Coatingmay be achieved by many methods well known in the imaging art (e.g.,solvent casting, knife coating, extrusion, etc.). Suitable substrates onwhich the compositions of the present invention may be supportedinclude, but are not limited to, metals (e.g., steel and aluminumplates, sheets, and foils); films or plates composed of variousfilm-forming synthetic or high polymers including addition polymers(e.g., polyvinylidene chloride, polyvinyl chloride, polyvinyl acetate,polystyrene, polyisobutylene polymers and copolymers), and linearcondensation polymers (e.g., polyethylene terephthalate,polyhexamethylene adipate, polyhexamethylene adipamide/adipate);nonwoven wood by-product based substrates such as paper and cardboard;and glass. Substrates may be transparent or opaque.

The photosensitive compositions of the present invention may containvarious materials in combination with the essential ingredients of thepresent invention. For example, plasticizers, coating aids,antioxidants, surfactants, antistatic agents, waxes, ultravioletradiation absorbers, and brighteners may be used without adverselyaffecting the practice of the invention. The various materials shouldpreferably not contain functional groups which are more basic than thealkoxyalkyl ester employed in the present invention (e.g., free amines,alkoxides, sulfides, amides, urethanes, imides, etc.) as defined above,in a molar amount higher than the molar amount of photoacid precursor.

In still other embodiments of the present invention, processes forforming an imaged article are provided.

One inventive process involves the formation of an imaged articlecomprising exposing an imageable article (as disclosed herein earlier)to radiation within a range absorbed by the photoinitiator present inthe imageable article to form a latent image bearing article andthereafter, applying ink to the latent image bearing article, therebyforming an imaged article. An alternative to the above process involvescontacting the latent image bearing article with a dye, instead of inkto form an imaged article.

Another inventive process for the formation of an imaged articlecomprises the steps of exposing an imageable article (as disclosedherein above) to a range absorbed by the photoinitiator present in theimageable article thereby forming a first latent image bearing article;contacting the first latent image bearing article with a hydrophilizingagent to form a second latent image bearing article; and thereafter,contacting the second latent image bearing article with a dye solutionto form an imaged article. In an alternate embodiment to this process,the second latent image bearing article is contacted with ink, insteadof a dye, to form an imaged article.

Additionally, an ammonium salt can be added to the formulation. Thisprovides for a process for fixing an imaged article comprising thesteps:

a) exposing an imageable article to radiation within a range absorbed bysaid photoinitiator to form a first latent imagebearing article;

b) heating said first latent image bearing article to a temperaturegreater than about 100° C. to form a second latent image bearingarticle;

c) cooling said heated latent image bearing article to below 40° C. toform a third latent image bearing article;

d) exposing said modified latent image bearing article to white light toform a fourth latent image bearing article;

e) contacting said fourth latent image bearing article withhydrophilizing agent to form a fifth latent image bearing article; and

f) applying ink to said fifth latent image bearing article to form animaged article.

Alternatively, the addition of an ammonium salt gives a wash off systemby the following process:

a) exposing an imageable article to radiation within a range absorbed bysaid photoinitiator to form a first latent image-bearing article; and

b) contacting said first latent image-bearing article with ahydrophilizing agent to form an imaged article.

The following non-limiting examples further illustrate the presentinvention.

EXAMPLES

The materials employed below were obtained from Aldrich Chemical Co.(Milwaukee, WI) unless otherwise specified. Materials were analyzed byone or more of the following techniques ¹ H NMR, infrared, and massspectroscopy; gel phase chromatography; and differential scanningcalorimetry. The term MEK means methyl ethyl ketone. Aluminum platesused for coatings in the following experiments were cleaned, degreasedlithograde alloy, brush grained, electrochemically grained, anodizedaluminum sheets. Exposures were conducted using a Berkey Ascor vacuumframe exposure unit (Berkey Technical Co., Woodside, NY) equipped with a2 kW Ascor Addalux Lamp No. 1406-01. A neutral density 21 step (0.15absorbance units/step) sensitivity guide (Stouffer Graphic ArtsEquipment Co., South Bend, IN) was used to measure the photosensitivityof the coatings prepared below.

The term solid step as used below refers to the highest numbered stepwhich is completely dyed by the dye solution. The term open step refersto the highest numbered step which is completely free of ink afterinking of the imaged plate. Rubb-Up™ Ink U-62 (Printing Development,Inc., Racine, Wis.) was used to ink plates described below. Primedpolyester film used in the following examples is described in U.S. Pat.No. 4,335,220 (Jun. 15, 1982; Coney).

EXAMPLE 1

This example describes the preparation of poly(methoxymethyl acrylate)in two steps.

To a solution of 5.0 g (69 mmol) acrylic acid and 6.14 g (76.1 mmol)chloromethyl methyl ether in 25 ml methylene chloride was added asolution of 7.72 g (76.3 mmol) triethylamine in 25 ml methylene chlorideat 5° C. The reaction mixture was allowed to warm to room temperatureand was stirred overnight, poured into aqueous sodium bicarbonate, andextracted with ether. The ether layer was dried over anhydrous magnesiumsulfate and concentrated in vacuo. The residue was distilled at 67°-70°C. and 90-100 torr pressure to give 4.61 g of methoxymethyl acrylate(39.7 mmol, 57% yield).

A solution of 1.0 g methoxymethyl acrylate and 0.01 gazobis(isobutyronitrile) (also known in the art as AIBN) in 1 ml toluenewas heated to 60° C. for 24 hr. The mixture was cooled and stirred withmethanol for 24 hr. The resultant glassy material was placed in a vacuumoven at 50° C. and 0.1 torr for 24 hr to give poly(methoxymethylacrylate).

EXAMPLE 2

This example demonstrates that photosensitive compositions of thepresent invention may be imaged directly without traditional developmentmethods, or alternatively, with aqueous development.

A photosensitive composition was prepared by mixing: 0.472 gpoly(methoxymethyl acrylate), 0.028 g diphenyliodoniumhexafluorophosphate 0.14 g 9,10-diethoxyanthracene and 5.0 ml MEK.

The photosensitive composition prepared above was filtered and coatedonto two aluminum plates with a #7 wire-wound rod (R&D Specialties,Webster, N.Y.; wet thickness, 0.023 mm) and heated to 85° C. for 5 min.The samples were exposed for 1 min as described above.

One plate was developed by washing with hot tap water to give apositive-tone photoresist pattern. The exposed regions of the plate werewet by the water while unexposed regions remained dry. During the waterrinse step the coating in the exposed areas was removed.

The other plate was not developed, but a negative-tone image wasobtained by dipping the plate into an aqueous solution of MethyleneBlue. The exposed areas turned blue while the unexposed areas did notchange color.

A solution of 17.5 g methoxymethyl acrylate and 0.26 g of AIBN in 18 mlMEK was heated to 60° C. for 24 hr, and then an additional 18 ml MEK wasadded. A solution using 0.5 ml of the polymer solution, 1.5 ml of a 10%solution of GANTREZ™ AN-139 (GAF Corp., Wayne, N.J.) in MEK,diphenyliodonium hexafluorophosphate, 9,10-diethoxyanthracene and 4.4 mlMEK was coated onto aluminum plates with a number 12 wire-wound rod andheated to 85° C. for 5 min. The samples were exposed for 10 sec asdescribed above. The sample was swabbed with a 10% aqueous solution oftetra(hydroxyethyl)ethylenediamine, and then hand inked to give an open2 step.

A sample was prepared with above solution coated on polyester, andexposed in the same manner for 5 seconds, then soaked in a 10% solutionof aqueous Methylene Blue to give an open 4 step.

EXAMPLE 3

This example describes the preparation of poly(tetrahydropyran-2-ylacrylate) in two steps.

A solution of 10.5 g (146 mmol, 10 ml) acrylic acid and 14.0 g (166mmol, 15.2 ml) dihydropyran in 40 ml dichloromethane was stirred at roomtemperature for one day. The mixture was washed with saturated aqueoussodium bicarbonate and the organic layer was concentrated in vacuo. Theresidue was distilled to give 5.93 g (38.0 mmol, 26% yield)tetrahydropyran-2-yl acrylate, bp 40° C. at 0.2 torr.

A solution of 2.8 g (18 mmol) tetrahydropyran-2-yl acrylate preparedabove and 0.028 g AIBN in 2.8 ml toluene was stirred at 60° C. for 24 hrto give a solution of poly(tetrahydropyran-2-yl acrylate). This solutionwas concentrated in vacuo to give the polymer.

Solution A was prepared by dissolving the polymer isolated above in 3.0ml MEK.

EXAMPLE 4

This example demonstrates that photosensitive compositions of thepresent invention may be imaged directly without development, oralternatively, with aqueous development.

A photosensitive composition was prepared by mixing: 1 ml Solution A(from Example 3), 0.0195 g diphenyliodonium hexafluorophosphate, 0.0195g 9,10-diethoxyanthracene, and 2.2 ml MEK.

The mixture prepared as described above was filtered and the filtratewere coated onto three aluminum plates with a #7 wire-wound rod (wetthickness 0.92 mil, metric conversion=0.023 mm) and heated to 85° C. for5 min. One sample was exposed for 5 sec as described above followed byrinsing with hot tap water. The exposed regions of the plates wereobviously more hydrophilic than the unexposed regions as observed by thebehavior of water spread on the surface. During the water rinse step thecoating in the exposed areas was removed.

A negative-tone image was obtained by dipping a second sample into a 10wt % aqueous solution of Methylene Blue. The exposed areas becamecolored by the dye while the unexposed areas remained unchanged.

A third sample gave a positive-tone image when immersed in water andrubbed with ink. The exposed areas remained clear while the unexposedareas became inked.

The water contact angles of the exposed and unexposed regions of thesesamples were measured using a goniometer: in the exposed region theadvancing contact angle was 24° while in the unexposed region theadvancing contact angle was 60°.

A fourth sample was prepared as above except that the coating substratewas polyester film. After exposure, the imaged article was dipped into asolution of Methylene Blue as described above to give a negative-toneimage.

EXAMPLE 5

Preparation of Poly(tetrahydropyran-2-yl acrylate) Solution: To asolution of 35.6 g tetrahydropyran-2-yl acrylate in 35.6 ml toluene wasadded 0.356 g AIBN. The mixture was stirred for 2 hr, heated to 60° C.for 14 hr, and then cooled. To the reaction mixture was added 37.8 mlMEK and the mixture was rotated until it became homogeneous. This isreferred to as Solution B.

The following coating solution was prepared: 20 ml Solution B, 9.7 gpoly(tetrahydropyran-2-yl acrylate), 24 ml toluene, 25.6 ml MEK, 0.39 gdiphenyliodonium hexafluorophosphate, 0.39 g 9,10-diethoxyanthracene, 44ml MEK.

EXAMPLE 6

Synthesis of tetrahydropyran-2-yl methacrylate (method A): a solution of25.0 g (290 mmol) methacrylic acid and 27.8 g (330 mmol) dihydropyran in80 ml of dichloromethane was stirred for 14 hr at room temperature. Thereaction mixture was thoroughly extracted with saturated aqueous sodiumbicarbonate, dried (MgSO₄) and concentrated in vacuo. The residue wasdistilled to give 1.84 g (10.8 mmol; 3.7% yield) tetrahydropyran-2-ylmethacrylate, bp 53° C. at 0.2 torr.

Synthesis of tetrahydropyran-2-yl methacrylate (method B): to a solutionof 25.8 g (0.3 mol) methacrylic acid and 1.8 g (0.011 mol)2,4-dinitrotoluene in 25.2 g (0.3 mol) dihydropyran was added 0.05 ml(0.0015 mol) concentrated hydrochloric acid. The reaction mixture wasallowed to stir at 50° C. for 25 hr. The hydrochloric acid wasneutralized with solid sodium bicarbonate and the mixture was filtered.The filtrate was distilled to give 46.5 g (0.273 mol, 91% yield)tetrahydropyran-2-yl methacrylate, bp 50° C. at 0.15 torr.

Preparation of poly(tetrahydropyran-2-yl methacrylate) solution: to asolution of 35.6 g tetrahydropyran-2-yl methacrylate in 35.6 ml toluenewas added 0.356 g AIBN. The mixture was stirred for 2 hr, then heated to60° C. for 14 hr, and finally cooled. To the reaction mixture was added37.8 ml MEK, and the mixture was rotated until it became homogeneous.This solution is referred to as solution C.

A coating solution was prepared by combining: 20 ml solution C, 0.39 gdiphenyliodonium hexafluorophosphate, 0.39 g 9,10-diethoxyanthracene, 44ml MEK. This coating solution was filtered and the filtrate was coatedonto aluminum plates using a #7 wire-wound rod (wet thickness 0.92 mil,metric conversion=0.023 mm) and heated to 85° C. for 5 min. Samples ofthe coated plate were exposed 3 sec as described above. The exposedregions of the plates were more hydrophilic than the unexposed regionsas observed by the behavior of water spread on the surface. Thesesamples gave positive-tone images when inked.

Prior to exposure, several other samples of the coated aluminum platewere placed in an oven at 50° C. for more than two weeks; when imagedthese samples showed no degradation in properties.

EXAMPLE 7

In a separate procedure, 1.0 wt % Bromphenol Blue and 0.57 wt %trioctylamine were added to the coating solution of Example 6 resultingin a color change from blue to yellow in the light struck areas.

EXAMPLE 8

Tetrahydropyran methacrylate (33.0 g) was combined with 0.33 g AIBN in33 ml MEK and heated to 60° C. for 24 hr, then cooled. This mixture wascombined with 33 ml MEK to give solution D.

Sample were coated and irradiated according to the conditions of Example7, but using the following formulation: 20 ml solution D, 0.39 gdiphenyliodonium hexafluorophosphate, 0.39 g 9,10-diethoxyanthracene, 44ml MEK.

After exposure samples were immersed in or in some cases swabbed with a10% aqueous solution of a hydrophilizing agent. Following treatment theexposed regions of the plates became more hydrophilic than exposedregions of untreated plates as determined by the ease of hand inking thesamples. These samples gave positive-tone images when inked.Alternatively, development with a 10% aqueous solution of sodiumbicarbonate immediately following exposure increases the hydrophilicityof the exposed regions.

Compounds which were found effective as hydrophilizing agents are:4-morpholinepropanesulfonic acid, 4-morpholineethanesulfonic acid (MES),β-hydroxy-4-morpholinepropanesulfonic acid sodium salt, sodium4-morpholinepropanesulfonate, sodium cysteate,tetrakis(2-hydroxyethyl)ethylenediamine, triethanolamine, andtriethanalamine hydrochloride. Solutions of the preceding hydrophilizingagents prepared using 10% sodium bicarbonate as the diluent wereparticularly effective.

EXAMPLE 9

A coating solution, prepared as described in Example 8, was filtered andthe filtrate was coated onto primed polyester film with a #7 wire-woundrod (wet thickness 0.92 mil, metric conversion=0.023 mm) and heated to85° C. for 5 min. The sample was exposed 40 sec as described above. Thesamples were then soaked in a 10% aqueous solution of a hydrophilizingagent and then in an aqueous solution of Methylene Blue (20 wt %). Thistreatment made the exposed regions of the samples much denser blue ascompared to an untreated sample. An open 3 step was observed.

EXAMPLE 10

This example demonstrates the use of an added polymer.

A coating formulation was prepared by combining: 1.5 ml Gantrez™ AN-139(10 wt % in MEK), 0.5 ml poly(tetrahydropyran-2-yl-methacrylate)solution (33 wt % in MEK), 0.078 g diphenyliodonium hexafluorophosphate,0.019 g 9,10-diethoxyanthracene, 4.4 ml MEK.

A dye solution was prepared by combining: 3 parts Methylene Bluesolution (10 wt % in water) and 1 part sodium bicarbonate solution (10wt % in water).

Solutions were coated with a #12 wire-wound rod (wet thickness 1.16 mil,metric conversion=0.029 mm) on primed polyester and dried in an oven at85° C. for 5 minutes. Exposures were generally less than 10 seconds. Thesystem has a sensitivity of better than 10 mJ/cm². The exposed sampleswere dyed in the bath by submersing the sample for 5 minutes at roomtemperature to give negative-tone images. Longer soak times did notimprove the density of the films. The samples were rinsed with water anddried. Soaking the samples in pure water at this stage did not leach thedye from the film.

EXAMPLE 11

A coating formulation was prepared as described below: 9.0 ml Gantrez™AN-139 solution (10 wt % in MEK), 3.0 mlpoly(tetrahydropyran-2-yl-methacrylate) (33 wt % in MEK), 0.468 gdiphenyliodonium hexafluorophosphate, 0.117 g 9,10-diethoxyanthracene,0.03 g of Bromophenol Blue, 30 ml trioctylamine solution (0.2% in MEK).

A solution of hydrophilizing agent was prepared as follows: 10 g sodiumbicarbonate, 10 g 4-morpholinoethanesulfonic acid, and 100 ml water.

The solution was coated onto aluminum and heated to 85° C. for 5 min andexposed for 40 sec, and then swabbed with the hydrophilizing solution.This sample was press tested and rated at 250,000 impressions underaccelerated abrasion testing.

EXAMPLE 12

This example shows that thickness of coating affects the density of thegenerated image, and illustrates the use and effectiveness of variousdyes.

In this example all solutions were coated with a #12 (coatingformulation 1, 0.027 mm wet thickness) or #20 (coating formulation 2,0.046 mm wet thickness) wire-wound rod on primed polyester and dried inan oven at 85° C. for 5 minutes. Exposures were generally less than 10seconds. The system has a sensitivity of better than 10 mJ/cm². Theexposed samples were dyed in the bath by submersing the sample for 5minutes at room temperature. Longer soak times did not improve thedensity of the films. The samples were rinsed with water and dried.Soaking the samples in pure water at this stage did not leach the dyefrom the film. The coating formulations and the dye bath formulationsare given below.

Coating formulation 1 (film system): 1.5 ml Gantrez™ AN-139 solution (10wt % in MEK), 0.5 ml poly(tetrahydropyran-2-yl-methacrylate) solution(33 wt % in MEK), 0.078 g diphenyliodonium hexafluorophosphate, 0.019 g9,10-diethoxyanthracene, 4.4 ml MEK.

Coating formulation 2 (film system): 1.5 ml Gantrez™ AN-139 solution (10wt % in MEK), 0.5 ml poly(tetrahydropyran-2-yl-methacrylate) solution(33 wt % in MEK), 0.078 g diphenyliodonium hexafluorophosphate, 0.019 g9,10-diethoxyanthracene, 3.5 ml MEK.

The following dye solutions in Dye bath formulations 1 and 2 wereprepared at 10 wt % in water.

Dye bath formulation 1: 26.25 parts Methylene Blue solution, 7.5 partsAzure A solution, 3.75 parts Thioflavin T, and 37.5 parts MalachiteGreen oxalate, and 25 parts sodium bicarbonate.

Dye bath formulation 2: 15 parts Methylene Blue solution, 50 parts AzureA solution, 10 parts Thioflavin T, and 25 parts sodium bicarbonatesolution.

                  TABLE 1                                                         ______________________________________                                                  MacBeth Densitometer                                                          Settings.sup.a  Coating                                             Dye         Green   Blue   Red  White Formulation.sup.b                       ______________________________________                                        Methylene Blue                                                                            2.89    1.17   2.13 1.54  1                                                   3.00    2.19   2.50 2.50  2                                       Azure A     3.04    2.07   2.50       1                                                   3.15    2.25   2.23 2.53  2                                       Thioflavin T                                                                              0.00    0.73   0.20       1                                                   0.00    1.05   0.04 0.26  2                                       Malachite Green                                                                           0.45    0.44   0.41       1                                       Oxalate     0.36    0.35   0.97 0.34  2                                       Dye Bath    2.22    2.03   2.14 1.99  1                                       Formulation 1                                                                 Dye Bath    3.07    2.58   2.22 3.20  2                                       Formulation 2                                                                 Dye Bath    2.22    2.58   3.07 3.20  2                                       Formulation 3                                                                 Marker                          2.68  1                                       ______________________________________                                         .sup.a Density values.                                                        .sup.b Formulation 2 is more concentrated than Formulation 1.            

EXAMPLE 13

A coating solution was prepared by combining: 1.5 ml Gantrez™ solution(10% by weight in MEK), 0.5 ml poly(tetrahydropyran-2-yl-methacrylate)solution (33% by weight in MEK), 0.078 g diphenyliodoniumhexafluorophosphate, 0.019 g 9,10-diethoxyanthracene, 4.4 ml MEK.

The solution was coated with a #12 wire-wound rod (wet thickness 1.08mil, metric conversion=0.027 mm) onto pieces of primed polyester asdescribed in Example 12. All samples were dried in an oven at 85° C. for5 minutes, and exposures were generally less than 10 seconds. Thissystem had sensitivity better than 10 mJ/cm². Exposed samples weresubmersed in dye bath formulation 2 for 5 minutes at room temperature.Negative-tone images resulted under these conditions.

When the following formulation was used for a dye bath: 3 partsMethylene Blue (10 wt % in water), 1 part sodium hydroxide solution(4-10 wt % in water), positive-tone images were observed.

EXAMPLE 14

A printing plate was prepared by coating aluminum sheets with theformulation from Example 10. The coated sample was cut into strips andevaluated for sensitivity to fluorescent room light exposure. The samplewas exposed through a step wedge using a Berkey-Ascor vacuum frame,exposed to room lighting for varying amounts of time, and then inked.Strips were exposed for 10 seconds to give 8 steps with no room lightexposure, 9 steps with 5 min room light exposure and 10 steps with 10min room light exposure.

The above experiment was rerun replacing 9,10-diethoxyanthracene with2-ethylanthracene in the coating formulation. Strips were exposedthrough a mask with a Berkey Ascor for 20 seconds and then exposed toroom light followed by inking. With no room light exposure the number ofsteps was 9. With 30 min room light exposure the number of steps wasstill only 9.

EXAMPLE 15

This example describes the synthesis of poly(tetrahydrofuran-2-ylmethacrylate).

To a solution of 10 g methacrylic acid in 10 ml dichloromethane wasadded a solution of 9.28 ml 2,3-dihydrofuran in 30 ml dichloromethane.The reaction was allowed to stir for 14 hr at room temperature. Themixture was washed with a saturated solution of sodium bicarbonate. Theorganic layer was dried with MgO/MgSO₄ and concentrated in vacuo. Theresidue was distilled at 38° C./0.3 torr, to give 6.2 g (34% yield) oftetrahydrofuran-2-yl methacrylate. A solution of 6.0 gtetrahydrofuran-2-yl methacrylate and 0.066 g AIBN in 6 ml of MEK washeated to 60° C. for two days and 12 ml of MEK was added. This solutionwas used for further evaluation.

This solution was evaluated according to Example 10 substituting theabove solution in place of tetrahydropyran-2-yl methacrylate. Thesolution was coated on aluminum and air dried for 30 min, exposed for 5sec, swabbed with the hydrophilizing solution in Example 11, and handinked to give an open 6 steps.

EXAMPLE 16

This example describes the synthesis of poly(ethoxyethyl methacrylate).

To a solution of 20 g methacrylic acid in 50 ml dichloromethane wasadded 19 g ethyl vinyl ether in 30 ml dichloromethane. The mixture wasstirred overnight at room temperature and poured into ether and washedwith a saturated aqueous solution of sodium bicarbonate until thesolution ceased effervescing. The organic layer was dried with MgO/MgSO₄and concentrated in vacuo. The residue was distilled at 25° C./0.1 torrto give 7.1 g (19% yield) of ethoxyethyl methacrylate. A mixture of 7.0g ethoxyethyl methacrylate and 0.076 g AIBN in 7 ml MEK was heated to60° C. for 24 hr and 7 ml MEK was added. This solution (solution E) wasused for further evaluation.

EXAMPLE 17

A coating formulation was prepared by combining: 2.0 ml solution E,0.078 g diphenyliodonium hexafluorophosphate, 0.0195 g9,10-diethoxyanthracene, and 3.5 ml MEK. This formulation was coatedusing a #12 wire wound rod (0.027 mm wet thickness) onto an aluminumplate and heated to 80° C. for 5 min, exposed for 20 sec and hand inkedto give an open 4 step.

EXAMPLE 18

A coating formulation was prepared by combining: 0.5 ml solution E,0.078 g diphenyliodonium hexafluorophosphate, 0.039 g9,10-diethoxyanthracene, 1.5 ml Gantrez™ AN-139 (as a 10 wt % solutionin MEK), and 4.4 ml MEK. This formulation was coated using a #12 wirewound rod (0.027 mm wet thickness) onto an aluminum plate and heated to80° C. for 5 min, exposed for 5 sec, swabbed with 10% aqueoustriethanolamine and hand inked to give an open 5 step.

EXAMPLE 19

This example describes the synthesis ofpoly(methacrylonitrile-cotetrahydropyran-2-yl methacrylate) (1:0.1).

A mixture of 5 g of tetrahydropyran-2-yl methacrylate and 0.19 gmethacrylonitrile and 0.048 g AIBN in 5 ml MEK was heated to 60° C. for24 hr and then cooled to room temperature. An additional 5 ml MEK wasadded and this mixture was used for further evaluation (solution F).

EXAMPLE 20

A coating formulation was prepared by combining: 2.0 ml solution F,0.078 g diphenyliodonium hexafluorophosphate, 0.0195 g9,10-diethoxyanthracene, and 4.4 ml MEK. The formulation was coated ontopolyester film using a #12 wire wound rod, dried at 85° C. for 5 min,exposed for 10 sec, and dyed with dye bath solution 2 (Example 12) togive a closed 6 step.

EXAMPLE 21

A coating formulation was prepared by combining: 0.5 ml solution F,0.078 g diphenyliodonium hexafluorophosphate, 0.039 g9,10diethoxyanthracene, 1.5 ml Gantrez™ AN-139 (as a 10 wt % solution inMEK), and 4.4 ml MEK. The formulation was coated onto aluminum using a#12 wire wound rod, dried at 85° C. for 5 min, exposed for 5 sec,swabbed with a solution of 10 g 4-morpholineethanesulfonic acid dilutedto 100 ml with a 10 wt % NaHCO₃ solution, and hand inked to give an open3 steps.

EXAMPLE 22

This example describes the synthesis of poly(itaconicanhydride-cotetrahydropyran-2-yl methacrylate).

A solution of 3.0 g tetrahydropyran-2-yl methacrylate, 0.65 g itaconicanhydride, and 0.038 g AIBN in 3 ml of MEK was heated to 60° C. for 24hr. An additional 2 ml MEK was added and this solution was used forfurther evaluation. A coating formulation was prepared from: 0.5 mlabove solution, 1.5 ml Gantrez™ AN-139 (as a 10 wt % solution in MEK),0.078 g diphenyliodonium hexafluorophosphate, 0.039 g9,10-diethoxyanthracene, and 4.4 ml MEK.

This formulation was coated onto an aluminum plate using a #12 wirewound rod (0.027 mm wet thickness), dried at 85° C. for 5 min, exposedfor 5 sec, swabbed with 10% aqueous triethanolamine solution, and handinked to give an open 7 step.

EXAMPLE 23

A coating formulation was prepared by combining: 0.5 mlpolytetrahydropyran-2-yl methacrylate (30 wt % in MEK), 1.5 mlstyrene/maleic anhydride copolymer (10 wt % in MEK), 0.078 gdiphenyliodonium hexafluorophosphate, 0.0195 g 9,10-diethoxyanthracene,and 3.5 ml MEK.

This formulation was coated onto an aluminum plate, dried at 85° C. for5 min, exposed for 10 sec, swabbed with a solution of 10 g4-morpholineethanesulfonic acid diluted to 100 ml with a 10 wt % NaHCO₃solution, and hand inked to give an open 4 step.

This formulation was coated onto primed polyester film using a #12 wirewound rod (0.027 mm wet thickness), dried at 85° C. for 5 min, exposedfor 10 sec dyed with dye bath solution 2 (Example 12) to give a closed 4step.

EXAMPLE 24

This example describes the synthesis of poly(methylmethacrylate-co-tetrahydropyran-2-yl methacrylate) 1:1.

A mixture of 3.0 g tetrahydropyran-2-yl methacrylate, 1.8 g methylmethacrylate, and 0.058 g AIBN in 5 ml MEK was heated to 60° C. for 24hr. After cooling an additional 5 ml MEK was added and this solution wasused below.

A coating formulation was prepared by combining 0.5 ml of the abovesolution of poly(methyl methacrylate-co-tetrahydropyran-2-ylmethacrylate), 1.5 ml Gantrez™ AN-139 (10 wt % solution in MEK), 0.078 gdiphenyliodonium hexafluorophosphate, 0.0195 g 9,10-diethoxyanthracene,and 4.4 ml MEK. This formulation was coated onto an aluminum plate,dried at 85° C. for 5 min, exposed for 10 sec, swabbed with thehydrophilizing solution of Example 11, and hand inked to give an open 3step.

The above coating solution was also coated with a #20 wire wound rod(10.046 mm wet thickness) onto primed polyester and dried at 85° C. for5 min. A 10 sec exposure was followed by soaking in dye bath formulation2 for 5 min. The coating produced in this manner had a density of 2.65in the exposed areas and a background of 0.09 in unexposed regions.

EXAMPLE 25

This example describes the synthesis of poly(methylmethacrylate-co-tetrahydropyran-2-yl methacrylate 3:1.

A mixture of 1.0 g of tetrahydropyran-2-yl methacrylate, 1.8 g of methylmethacrylate, and 0.039 g of AIBN in 3 ml of MEK was heated to 60° C.for 24 hr. An additional 60 ml MEK was added and the resulting solutionwas added dropwise to a vigorously stirred container holding 180 mlmethanol. The precipitated polymer was collected as a white solid whichweighed about 2 g after drying. A 30 wt % solution of this material inMEK was prepared and used for further evaluation.

A coating formulation was prepared by combining 0.5 ml of the abovesolution of poly(methyl methacrylate-co-tetrahydropyran-2-ylmethacrylate), 1.5 ml Gantrez™ AN-139 (10 wt % solution in MEK), 0.078 gdiphenyliodonium hexafluorophosphate, 0.0195 g 9,10-diethoxyanthracene,and 4.4 ml MEK. This formulation was coated onto an aluminum plate,dried at 85° C. for 5 min, exposed for 40 sec, swabbed with thehydrophilizing solution of Example 11, and hand inked to give an open 2step.

The above coating solution was also coated with a #20 wire wound rod(0.046 mm wet thickness) onto primed polyester and dried at 85° C. for 5min. A 20 sec exposure was followed by soaking in dye bath formulation 2for 5 min to give a closed 7 step. The coating produced in this mannerhad a density of 3.07 in the exposed areas and a background of 0.09 inunexposed regions.

EXAMPLE 26

A coating formulation was prepared by combining 0.5 ml of the abovesolution of poly(tetrahydropyran-2-yl methacrylate) (30 wt % solution inMEK), 1.5 ml of Gantrez™ AN-139 (10 wt % solution in MEK), 0.078 gtristrichloromethyl triazine, 0.0195 g of 9,10-diethoxyanthracene, and3.5 ml of MEK.

This formulation was coated with a #12 wire wound rod (0.027 mm wetthickness) on aluminum plates, dried at 80° C. for 5 min, and exposedfor 90 sec, swabbed with the MES hydrophilizing solution (Example 11)and hand inked to give an open 4 step.

The above coating formulation was also coated with a #20 wire wound rodon primed polyester and dried in an oven at 80° C. for 5 minutes.Exposures were for 120 seconds followed by soaking in dye bathformulation 2 for 5 minutes to give a closed 2 step.

EXAMPLE 27

A coating formulation was prepared by combining 0.5 ml of the abovesolution of poly(tetrahydropyran-2-yl methacrylate) (30 wt % solution inMEK), 1.5 ml of Gantrez™ AN-139 (10 wt % solution in MEK), 0.078 gtriphenylsulfonium hexafluorophosphate, 0.0195 g of9,10-diethoxyanthracene, and 3.5 ml of MEK.

This formulation was coated with a #12 wire wound rod (0.027 mm wetthickness) on aluminum plates, dried at 80° C. for 5 min, exposed for 10sec, swabbed with 10% aqueous triethanolamine solution and hand inked togive an open 7 step.

The above coating formulation was also coated with a #20 wire wound rod(0.046 mm wet thickness) on primed polyester and dried in an oven at 80°C. for 5 minutes. Exposures were performed 10 seconds followed bysoaking in dye bath formulation 2 for 5 minutes to give a closed 6 step.

EXAMPLE 28

A coating formulation was prepared by combining 0.5 mL of the abovesolution of poly(tetrahydropyran-2-yl methacrylate) (30 wt % solution inMEK), 1.5 mL of GANTREZ™ AN-139 (10 wt % solution in MEK), 0.078 gdiphenyliodonium hexafluorophosphate, 0.0195 g of9,10-diethoxyanthracene, and 3.5 mL of MEK.

This formulation was coated with a #12 wire-wound rod (0.027 mm wetthickness) onto aluminum plates, dried at 80° C. for 5 minutes, exposedfor 10 seconds, swabbed with a 10% aqueous solution of triethanol aminethat has been treated with 12 molar hydrochloric acid to a pH of 7, andhand inked to give an open 7 step.

EXAMPLE 29

The example demonstrates the use of ethyl violet to obtain a printoutimage after exposure, and to stabilize the non-imaged regions to whitelight (room light) exposure.

A coating formulation was prepared by combining 0.15 g ofpoly(tetrahydropyran-2-yl methacrylate), 0.15 g of GANTREZ™ AN-139,0.078 g diphenyliodonium hexafluorophosphate, 0.0195 g of9,10-diethoxyanthracene, 1.0 mL of ethyl violet solution (0.03 g in 10mL of MEK) and 1.0 mL of MEK.

This formulation was coated with a #12 wire-wound rod onto aluminumplates, dried at 80° C. for 5 minutes, exposed for 5 seconds, swabbedwith a 10% aqueous solution of triethanolamine that has been treatedwith 12 molar hydrochloric acid to a pH of 7, and hand inked to give anopen 3 step.

A second sample prepared in this manner was image-wise exposed in aBerkey Ascor device for 5 seconds and then flood exposed to room lightsfor 1.25 hours. The sample was swabbed with a 10% aqueous solution oftriethanolamine that has been treated with 12 molar hydrochloric acid toa pH of 7, and hand inked to give an open 3 step.

Coating solutions as described above are not stable at room temperatureover a period of several days, however, if the GANTREZ™ resin is omittedfrom the coating solution and added just prior to coating, the solutionsare stable.

EXAMPLE 30

This example illustrates the white light stability of a formulationutilizing 2-ethylanthracene and ethyl violet.

A coating formulation was coated with a #12 wire-wound rod onto aluminumplates, dried at 80° C. for 5 minutes, exposed for 50 seconds, swabbedwith the hydrophilizing solution in example 11 and hand inked to give anopen 8 step.

A second sample prepared in this manner was image-wise exposed in aBerkey Ascor device for 50 seconds and then flood exposed to room lightsfor 3.5 hours. The sample was hand inked in water to give an open 4step.

EXAMPLE 31

This example illustrates the wash off system that is obtained when usingan ammonium salt in the formulation.

A coating formulation was prepared by combining 0.30 g ofpoly(tetrahydropyran-2-yl methacrylate), 0.30 g of GANTREZ™ AN-139,0.156 g di(dodecylphenyl)iodonium hexafluoroantimonate, 0.039 g of9,10-diethoxyanthracene, 0.05 g of tetrabutylammonium chloride 1.0 mL ofethyl violet solution (0.03 g in 10 mL of MEK), and 3.0 mL of MEK.

This formulation was coated with a #12 wire-wound rod onto aluminumplates, dried at 80° C. for 5 minutes, exposed for 60 seconds, swabbedwith a 10% aqueous solution of triethanol amine that has been treatedwith 12 molar hydrochloric acid to a pH of 7. At this point the coatingin the background came off the produce a clean aluminum surface. Handinking gave an open 4 step.

EXAMPLE 32

The example illustrates a wash off system with diallylpiperidiniumbromide and ethyl violet that remains stable after extended white lightexposure (at least 90 h).

A coating formulation was prepared by combining 1.0 mL ofpoly(tetrahydropyran-2-yl methacrylate) (30 wt % solution in MEK), 3.0mL of GANTREZ™ AN-139 (10 wt % solution in MEK), 0.078 g ofdi(dodecylphenyl)iodonium hexafluoroantimonate, 0.039 g of9,10-diethoxyanthracene, 0.01 g of diallylpiperidimium bromide and 1.0mL of ethyl violet solution (0.03 g in 10 mL of MEK).

This formulation was coated with a #12 wire-wound rod onto aluminumplates, dried at 80° C. for 5 minutes, exposed for 60 seconds, swabbedwith a 10% aqueous solution of triethanol amine that has been treatedwith 12 molar hydrochloric acid to a pH of 7. At this point the coatingin the background came off the produce a clean aluminum surface. Thesample was then flood exposed with room light for 90 hours and handinked to give an open 5 step.

EXAMPLE 33

This example illustrates a system that does not wash off but utilizes anammonium salt to generate a stable image by a postheating step.

A sample prepared as described in example 32 was exposed for 60 secondsand then heated to 120° C. for 10 minutes and then flood exposed withroom light for 12 h. The sample was either swabbed with water or a 10%aqueous solution of triethanol amine that has been treated with 12 molarhydrochloric acid to a pH of 7, and hand inked to give an open 4 step.In this instance the background coating did not come off on swabbing.

EXAMPLE 34

This example illustrates a second example similar to example 32 with adifferent ammonium salt.

A sample was prepared as described in example 32 exceptdiallylpiperidinium bromide was replaced by methyltriallylammoniumbromide. The sample was exposed for 60 seconds, swabbed with a 10%aqueous solution of triethanol amine that has been treated with 12 molarhydrochloric acid to a pH of 7. At this point the coating in thebackground came off and produce a clean aluminum surface. The sample wasthen flood exposed with room light for 90 hours and hand inked to givean open 5 step.

Reasonable variations and modifications are possible from the foregoingdisclosure without departing from either the spirit or scope of thepresent invention as defined in the claims.

We claim:
 1. An imageable article comprising a photosensitivecomposition coated on a substrate, said photosensitive compositioncomprising:(a) a photoinitiator which generates an acid upon exposure toradiation; and (b) a polymer having acid labile groups pendant from thepolymer backbone, said acid labile pendant groups being represented bythe following formula: ##STR5## wherein: R¹ and R² each representhydrogen or a C₁ to C₁₈ alkyl group with the proviso that at least oneof R¹ and R² must be hydrogen; R³ represents a C₁ to C₁₈ alkyl group; orany two of R¹, R², and R³ together form a substituted or unsubstitutedring containing from 2 to 36 carbon atoms; and T represents a divalentlinking group connected to the polymer backbone and contains a total offrom 0 to about 18 carbon atoms where up to one of each three carbonatoms can be replaced with nitrogen, oxygen, or sulfur atoms, orcombinations thereof.
 2. An imageable article according to claim 1wherein said photoinitiator is one selected from the group consisting ofonium salts and photolyzable organic halogen compounds.
 3. An imageablearticle according to claim 1 wherein said photoinitiator is one selectedfrom the group consisting of: ##STR6## wherein: A and B are individuallysubstituted or unsubstituted aryl groups with a total of from 4 to 20carbon atoms;W is selected from the group consisting of a carbon tocarbon bond; oxygen; sulfur; ##STR7## R⁶ is aryl, acyl, or R⁷ -C-R⁸ ; R⁷and R⁸ are individually hydrogen, an alkyl group of 1-4 carbon atoms, oran alkenyl group of 2 to 4 carbon atoms; p is 0 or 1; and Q is an anionwith a pK_(a) less than about 16 and an oxidation potential of greaterthan about 0.7 V.
 4. An imageable article according to claim 1 whereinsaid polymer is one selected from the group consisting of:polyacrylates, polymethacrylates, polystyrenes, acrylonitrile-styrenecopolymers, butadiene-styrene copolymers, polyolefins, polyesters,polyethers, polycarbonates, and polysulfides.
 5. An imageable articleaccording to claim 1 wherein said divalent linking group T does notcontain any basic functional groups selected from the group consistingof: free amines, alkoxides, sulfides, amides, urethanes, and imides. 6.An imageable article according to claim 1 wherein said photosensitivecomposition further comprises a homo- or copolymer of an acid anhydride.7. An imageable article according to claim 1 wherein the photosensitivecomposition further comprises ethyl violet.
 8. An imageable articleaccording to claim 1 wherein the photosensitive composition furthercomprises a quaternary ammonium salt.
 9. An imageable article accordingto claim 8 wherein the photosensitive composition further comprisesethyl violet.